// 第二题：2-1
const fp = require('lodash/fp')
// 数据
// horsepower 马力，  dollar_value 价格， in_stock 库存
const cars = [
    { name: 'Ferrari FF', horsepower: 660, dollar_value: 700000, in_stock: true },
    { name: 'Spyker C12 Zagato', horsepower: 650, dollar_value: 648000, in_stock: false },
    { name: 'Jaguar XKR-S', horsepower: 550, dollar_value: 132000, in_stock: false },
    { name: 'Audi R8', horsepower: 525, dollar_value: 114200, in_stock: false },
    { name: 'Aston Martin One-77', horsepower: 750, dollar_value: 1850000, in_stock: true },
    { name: 'Pagani Huayra', horsepower: 700, dollar_value: 1300000, in_stock: false }
]
const splitStr = _str => str => `${_str}${str}`
const title = splitStr('2-')
const _l = defaultString => (str, ...args) => console.log.apply(null, [`${defaultString}`, ...args]);
const l = (str, ...arg) => (_l(`${title(str)}: => `))(str, ...arg);

let isLastInStock = function (cars) {
    let last_car = fp.last(cars)
    return fp.prop('in_stock', last_car)
}
isLastInStock = fp.flowRight(fp.prop('in_stock'), fp.last)
l(1, isLastInStock(cars))

// 第二题：2-2
isFirstCarName = fp.flowRight(fp.prop('name'), fp.first)
l(2, isFirstCarName(cars))

// 第二题：2-3
let _average = function (xs) {
    return fp.reduce(fp.add, 0, xs) / xs.length
}
let averageDollarValue = function (cars) {
    let dollar_values = fp.map(function (car) {
        return car.dollar_value
    }, cars)
    return _average(dollar_values)
}
averageDollarValue = fp.compose( _average, fp.map(car => car.dollar_value) )
l(3, averageDollarValue(cars))

// 第二题：2-4
let _underscore = fp.replace(/\W+/g, '_')
let sanitizeNames = fp.map(item => (fp.flowRight(_underscore, fp.toLower))(item) )
l(4, sanitizeNames(['Hello World']))